Investigation of the Roles of NCN and HNO Reactions on NOx Formation in Combustion Processes

在燃烧过程中，NCN自由基和HNO作为中间体在氮氧化物（NOx）的形成中起着重要的作用。用于开发和优化污染物减排策略的详细和复杂的反应机制依赖于许多基本气相反应的准确速率常数参数化。虽然已经做了很多工作来开发NOx形成的子机制，但近年来已经很清楚，NCN自由基促进no形成的途径在模型中没有得到适当的实现。在该项目的第一个资助期内，可以首次对一些最重要的NCN反应进行直接速率常数测量。将继续对选定的双分子NCN反应进行类似的激波管研究，以组装完整的NCN高温机制。利用激光吸收技术，包括新开发的中红外探测系统，将测量许多物种（NCN， OH， CN， HCN， CH， N）的浓度-时间曲线。此外，还将进行额外的实验来澄清一些有争议的生成焓值和NCN的高温吸收截面。所有数据的结合产生了一个纯粹基于实验的神经网络子机制，该子机制将在更复杂的反应系统的实验中得到验证，并应用于现代火焰机制。火焰模拟将显示是否实现了总体研究目标，即火焰中NOx形成的可靠建模。就HNO而言，在第一个资助期间，这种难以测量的物种首次可以在冲击波后检测到。对调频检测系统的进一步优化将使HNO + O2、H和OH等反应的速率常数测量成为可能。到目前为止，关于HNO动力学的高温数据很少，而且大部分是分散的；因此，这些测量为改进的HNO火焰模型提供了基础，该模型既能快速形成no，也能转化燃料n。

NCN radicals and HNO play important roles as intermediates in the formation of nitrogen oxides (NOx) in combustion processes. The detailed and complex reaction mechanisms used to develop and optimize pollutant reduction strategies rely on accurate rate constant parametrizations for many elementary gas phase reactions. Although much work has been done to develop NOx formation submechanisms, in recent years it has become clear that the NCN radical pathway to prompt-NO formation is not properly implemented in the models.During the first funding period of this project, direct rate constant measurements of some of the most important NCN reactions could be performed for the first time. Similar shock tube investigations of selected bimolecular NCN reactions will be continued in order to assemble a complete NCN high temperature mechanism. Using laser absorption techniques, including a newly developed mid-IR detection system, concentration-time profiles of many species (NCN, OH, CN, HCN, CH, N) will be measured. Moreover, additional experiments will be performed to clarify the somewhat disputed values of the enthalpy of formation and the high temperature absorption cross section of NCN. The combination of all data result in a purely experimentally based NCN submechanism that will be validated against experiments of more complex reaction systems and implemented into modern flame mechanisms. Flame simulations will show if the overarching research goal, i.e. a reliable modeling of NOx formation in flames, will be met. In terms of HNO, during the first funding period this difficult to measure species could be detected behind shock waves for the first time. Further optimization of the frequency modulation detection system will enable rate constant measurements of selected HNO reactions including HNO + O2, H and OH. So far, high temperature data on HNO kinetics are rare and largely scattered; hence these measurements provide the basis for an improved HNO flame model for both prompt-NO formation and fuel-N-conversion.